1. Field of the Invention
This invention relates to semiconductor device packages, and more specifically, relates to low profile semiconductor device packages with multiple die.
2. Discussion of the Related Art
Semiconductor device packages are used in many digital applications that provide improvements over prior art analog applications. For example, Class D audio amplifiers are smaller, lighter, cooler and quieter than analog audio amplifiers, and provide extended battery life compared to the power hungry analog devices. Class D amplifiers also provide improved switching speeds over Class AB linear amplifiers, and, accordingly reduce power loss and reduce sound distortions in sound output. Class D amplifiers can be implemented, for example, using multiple low profile semiconductor device packages, such as a TO-220 package.
In addition to Class D audio amplifiers, low profile semiconductor device packages, such as the TO-220 package, are also useful in a range of other applications. For example, low profile device packages are used in lighting circuit applications and are also used as switching devices in notebook computers.
Referring now to the Figures in which like reference numerals refer to like elements, there is shown in FIGS. 1A and 1B a front elevational view and a right elevational view of an example prior art, low profile, semiconductor device package 100, such as the TO-220 package. As shown in FIGS. 1A and 1B, package 100 includes a mounting hole section 130. This mounting hole section is provided and used to mount package 100 to, for example, a heat sink in a notebook computer adapter. As shown in FIG. 1A, package 100 further includes a lead frame 102 that includes a single die pad 104 for receiving at least one semiconductor die 106, preferably a MOSFET die, although other die forms, such as diodes, insulated gate bipolar transistors (IGBTs), or the like can be used. The lead frame also includes five terminal leads 110, 112, 114, 116, and 118 protruding from the lead frame and extending from one edge of the package beyond the periphery of an insulated housing 108 for external connection. Of course, one skilled in the art will recognize that lead frame 102 may include something other than five terminal leads, for example, three terminal leads.
Assuming semiconductor die 106 is a MOSFET die, as shown in FIG. 1A, terminal lead 114 is electrically connected to die pad 104 and in turn to the drain electrode of the MOSFET die. The source and gate electrodes of the die may be electrically connected by bond wires to one or more terminals, other than terminal lead 114. In this example, the source electrode is electrically connected to terminal leads 110, 112, and 116 by bond wires 120, 121, and 122 and the gate electrode is electrically connected to terminal lead 118 by bond wire 123. Of course, one skilled in the art will recognize that these terminal assignments can vary depending on the application.
It should also be noted that a full-height three-pin full-pak with a split lead frame used for common anode and series diode configurations is also known in the industry. For example, see device package 1300 in FIG. 13.
Referring now to the FIGS. 2A and 2B there is shown a front elevational view and a right elevational view of another example prior art, low profile, semiconductor device package 200. Package 200 is similar to device package 100, with a lead frame 202 that includes a single die pad and three or five terminal leads, for example, but has a reduced height, not including a mounting hole section 130. Device package 200 may be, for example, a short-height TO-262 package.
Overall, prior art semiconductor device packages, such as packages 100 and 200, are useful in many applications and provide several benefits in the industry. For example, the device packages are inexpensive and easy to fabricate. Furthermore, the packages are small, lightweight, and have low profiles thereby reducing the cost, size, and weight of high volume consumer applications. In addition, package 200 is useful for reduced height applications. However, it is observed that these prior art device packages are not always suitable for packaging circuits that require multiple die.
For example, referring to FIG. 3, there is shown a conventional half-bridge circuit 300, such as that used in a Class D amplifier. Circuit 300 comprises a high side N-Channel MOSFET 310 and a low side N-Channel MOSFET 320. Of course, one skilled in the art will recognize that MOSFETs 310 and 320 may also be of the P-Channel type. Each MOSFET provides a switching function under the control of a suitable control circuit 302 that is connected to gate 316 of MOSFET 310 and to gate 326 of MOSFET 320, the specific control circuit depending on the application. To complete the half-bridge circuit, source 314 of MOSFET 310 is connected to drain 322 of MOSFET 320. The half-bridge circuit interconnects to a specific circuit application through drain 312 of MOSFET 310 and source 324 of MOSFET 320.
In order to implement the half-bridge circuit of FIG. 3 using a low profile semiconductor device package, such as package 100 or package 200, two device packages are required, one package for a MOSFET die 310 and a second package for a MOSFET die 320. However, the use of multiple low profile device packages to implement circuits, such as this half-bridge circuit, increases part and assembly costs for end applications, creates the need for additional circuit board space, and also creates the need for larger heat sinks.